Butadiene telomerization catalyst precursor preparation

ABSTRACT

Use a solvent blend that contains 1methoxy-2,7-octadiene and an alkanols rather than the alkanols by itself to prepare a catalyst precursor suitable for use in butadiene telomerization.

The present application is a divisional application of and claimspriority to U.S. patent application Ser. No. 15/030,625, filed on Apr.20, 2016, which is a national stage entry of International ApplicationPCT/US2014/068483, filed on Dec. 4, 2014, which claims priority to U.S.Provisional Patent Application No. 61/915,781, filed Dec. 13, 2013, allof which are incorporated by reference herein in their entirety.

This invention relates generally to preparation of a butadienetelomerization catalyst precursor.

U.S. Pat. No. 8,558,030 B2 discloses a process for telomerizingbutadiene that includes contacting butadiene and an organic hydroxylcompound represented by formula ROH, where R is a substituted orunsubstituted C₁-C20 hydrocarbyl and the organic hydroxyl compound isnot glycerol in a reaction fluid in the presence of a palladium catalystand a phosphine ligand represented by formula PAr₃, wherein each Ar isindependently a substituted or unsubstituted aryl having a hydrogen atomon at least one ortho position, at least two Ar groups areortho-hydrocarbyloxyl substituted aryls. The phosphine ligand has atotal of 2, 3, 4, 5 or 6 substituted or unsubstituted C₁-C20hydrocarbyloxyls and, optionally, two adjacent substituents on an Argroup can be bonded to form a 5- to 7-membered ring.

A typical process for preparing a catalyst precursor used intelomerization of butadiene to produce 1-octene involves batchwisedissolution of one equivalent of palladium acetyl acetonate([Pd(acac)₂]) and two equivalents of a triarylphosphine (PAr₃) (e.g.triphenyl phosphine (TPP) or tris(5-chloro-2-methoxyphenyl)phosphine(TCMPP)) in methanol. This precursor is stabilized by acetic acid thatis also added during pre-catalyst solution make-up, resulting in a saltthat is soluble in methanol and in a +2 oxidation state. Undertelomerization reaction conditions, the palladium (Pd) (II)-containingcatalyst precursor appears to be reduced by a sodium methoxide promoterin methanol in the presence of 1,3-butadiene to a palladium(0) bisphosphine complex designated as [Pd(PPh₃)₂]. Subsequent addition of1,3-butadiene results in formation of a (PPh₃)_(1 or 2)-Pd-(octadienyl)complex. Further reaction with methanol leads to formation of either1-methoxy-2,7-octadiene (MOD-1) or 3-methoxy-1,7-octadiene (MOD-3). Atlow temperatures such as those within a range of from 25° centigrade (°C.) to 60° C., the reaction can include an induction period due toreduction of the Pd(II) species to an active Pd(0) complex. Thisreduction can occur more slowly than the telomerization reaction, andtherefore results in an induction period before the telomerizationreaction attains maximum rate. A desire exists to reduce, preferablysubstantially reduce and more preferably eliminate the induction period.

Hausoul et al. in “Facile Access to Key Reactive Intermediates in thePd/PR₃-Calalyzed Telomerization of 1,3-Butadiene”, Angew. Chem. Int. Ed,2010, 49, 7971-7975, notes that Pd-catalyzed telomerization of1,3-dienes is an important atom-efficient transformation that providesan economically attractive route to production of C₈ bulk chemicals suchas 1-octanol and 1-octene. Hausoul reports on preparation of catalystcomplexes that include phosphine ligands such as PPh₃(triphenylphosphine), TOMPP (tris(2-methoxyphenyl)phosphine) and TPPTS(3,3′,3″-phosphinidynetris(benzenesulfonic acid) trisodium salt). Thepreparation uses a solvent mixture such as a 1:1 volume mixture ofdichloromethane and methanol.

Benn et al., in “Intermediates in the Palladium-Catalyzed Reactions of1,3-Dienes. 2. Preparation and Structure of (η¹,η³-OctadiendiyepalladiumComplexes”, Organometallics 1985, 4, 1945-1953, reports preparation of aseries of (η¹,η³-octadiendiyl)palladium complexes, [Pd(L)(η¹,η³-C₈H₁₂)]and [Pd(L) η¹,η³-Me₂C₈H₁₀)] by reacting bis(η³-2-methylallyl) palladiumwith donor ligands and butadiene or isoprene and tetrahydrofuran (THF)as a solvent.

Behr et al., in “Octadienyl-Bridged Bimetallic Complexes of Palladium asIntermediates in Telomerization Reactions of Butadiene”, Organometallics1986, 5, 514-518, discusses preparation of title compounds using asolvent such as methanol, THF or benzene.

Hausoul et al., in “Mechanistic Study of the Pd/TOMPP-CatalyzedTelomerization of 1,3-Butadiene with Biomass-Based Alcohols: On theReversibility of Phosphine Alkylation”, ChemCatChem 2011, 3, 845-852,discloses testing of several catalyst systems with emphasis uponPd/TOMPP (tris(2-methoxyphenyl)phosphine).—

Vollmüller et al, in Palladium-Catalyzed Reactions for the Synthesis ofFine Chemicals, 16, Highly Efficient Palladium-Catalyzed Telomerizationof Butadiene with Methanol”, Adv. Synth. Catal. 2001, 343, No. 1, pages29-33, details use of methanol under argon to prepare a catalystprecursor from triphenylphosphine and palladium(II) acetate.

Jackstell et al., in “An Industrially Viable Catalyst System forPalladium-Catalyzed Telomerizations of 1,3-Butadiene with Alcohols”,Chem. Eur. J. 2004, 10, 3891-3900, describe use of methanol inpreparation of catalyst precursors.

Vollmüller et al., in “Palladium-Catalyzed Reactions for the Synthesisof Fine Chemicals, 14, Control of Chemo-and Regioselectivity in thePalladium-Catalyzed Telomerization of Butadiene with Methanol—Catalysisand Mechanism, 2000, 8, 1825-1832, usesmono(phosphane)palladium(0)-diallyl ether complexes,Ar₃P—Pd(CH₂═CHCH₂)₂O, as catalysts to dimerize 1,3-diene, specificallybutadiene, in the presence of a nucleophile, in this case methanol.MOD-1 is a primary product, but MOD-3 and other materials are present asbyproducts. Vollmüller et al. states that the catalyst does not need tobe activated (e.g. by ligand dissociation, reduction, etc.) beforeentering the catalyst cycle, but does not discuss precatalyst stability.

Hausoul et al., in “Mechanistic study of the Pd/TOMPP-CatalyzedTelomerization of 1,3-Butadiene: Influence of Aromatic Solvents onBis-Phosphine Complex Formation and Regio Selectivity”, Organometallics,2013, 32, pages 5047-5057, reports on Pd/TOMPP-catalyzed telomerizationof 1,3-butadiene with phenols such as p-cresol, guaiacol and creosol.

European Patent Specification (EP) 0 561 779 B1 (Bohley et al.) relatesto a process for producing 1-octene. The process comprises: i) reacting1,3-butadiene with a primary aliphatic alcohol (e.g. methanol, ethanol,propanol, butanol, ethylene glycol, propylene glycol and glycerol) oraromatic hydroxyl compound having formula R—H (e.g. phenol,benzylalcohol, cresols, xylenols, naphtol, polyhydric compounds such asresorcinol, hydroquinone and pyrocatechol as well as alkyl-, alkoxy-and/or halogen-substituted aromatic compounds such as methoxyphenol andp-chlorophenol) in the presence of a telomerization catalyst comprisingpalladium and a tertiary phosphorous ligand compound to form a1-substituted-2,7-octadiene of formula CH₂═CH—CH₂—CH₂—CH₂—CH═CH—CH₂—R inwhich R represents the residue of the primary aliphatic alcohol oraromatic hydroxy compound; ii) subjecting the1-substituted-2,7-octadiene to hydrogenation in the presence of ahydrogenation catalyst to form a 1-substituted octane of formulaCH₃—CH₂—CH₂—CH₂—CH₂—CH₂—CH₂—CH₂—R; and iii) decomposing the1-substituted octane in the presence of a suitable catalyst to form1-octene. Both palladium(II) compounds and palladium(0) complexes may beused as the catalyst. A catalyst promoter such as an alkali or alkalineearth metal salt appears to be advantageous. '779 teaches that anysolvent that will solubilize 1,3-butadiene, the activehydrogen-containing compound and the catalyst, ligand and optionalpromoter components may be used in the process. Suitable inert solventsare (cyclo)-alkanes, aromatic compounds, a polar solvent such as atertiary alcohol, an amide, a nitrile compound, a ketone, an estercompound, an ether compound, dimethylsulfoxide, sulpholane, and water.While the temperature is not critical, it is normally between ambienttemperature and 150° C., preferably 50-100° C., and more preferably70-100° C. Pressure is not critical, but is generally between 1 and 40bars, preferably between 5 and 30 bars and most preferably between 10and 20 bars.

In some aspects, this invention is a process for preparing atelomerization catalyst precursor used in telomerization of butadienethat comprises dissolving one equivalent of palladium acetyl acetonateand from one to three equivalents of a phosphine in a solvent blend thatcomprises methanol and 1-methoxy-2,7-octadiene under conditionssufficient to yield a catalyst precursor solution that comprises an arylphosphine-palladium octadienyl complex represented formulaically eitheras [(Ar_(n)PR_(3−n)))_(x)PdY] or as [(Ar_(n)PR_((3−n)))_(x)PdY]⁺ whereinR is an alkyl or heteroatom-containing alkyl moiety with 1 to 12 carbonatoms, Ar is an aryl moiety or substituted aryl moiety, x=1 or 2, n=1, 2or 3, and Y is a ligand derived from methoxyoctadiene and whereinillustrative ligands include 1-methoxy-2,7-octadiene (MOD-1) where nocharge is present or octadienyl when a positive charge is present. Thecatalyst precursor resulting from this process surprisingly entersdirectly into a telomerization reactor's catalytic cycle with noactivation step or induction period required. Elimination of theactivation step equates to increases in conversion and capacity. Inaddition, this catalyst precursor is more stable than a catalystprecursor prepared in the absence of 1-methoxy-2,7-octadiene (MOD-1).Under normal pre-catalyst storage conditions (Pd content of 0.1 wt % to1 wt %, temperature within a range of from 0° C. to 100° C., preferablyfrom 5° C. to 60° C. and pressure within a range of from 0 psig (0 KPa)to 30 psig (206.8 KPa)), Pd(II) complexes are reduced slowly to neutralPd (0) complexes such as Pd(PPh₃)₃ or Pd(TCMPP)₂(CH₂═C{(C═O)Me}₂. ThesePd complexes are substantially less soluble in methanol than theinitially formed Pd complex and can precipitate on process equipmentsurfaces with which they come in contact, leading to plugging. Theaddition of MOD-1 imparts a degree of resistance to formation of suchinsoluble complexes, thereby improving process operability andreliability relative to catalyst precursor preparation with onlymethanol as a solvent.

In some aspects, this invention is a process for preparing atelomerization catalyst precursor used in telomerization of butadienethat comprises dissolving one equivalent of palladium acetyl acetonateand from one to three equivalents, preferably from one to twoequivalents, of a tertiary phosphine ligand in a solvent that comprisesmethanol and, optionally, 1-methoxy-2,7-octadiene under conditionssufficient to yield a catalyst precursor solution wherein the tertiaryphosphine ligand is represented formulaically as R¹PR² and where R¹ isan aryl moiety or a substituted aryl moiety or an alkyl moiety orheteroatom-containing alkyl moiety wherein the heteroatom is oxygen with1 to 12 carbon atoms, and R² is independently a heterocyclicoxaadamantyl group.

Phosphine-containing heterocyclic oxaadamantyl groups (PR²) are suitablyrepresented schematically as shown below wherein R¹ is as defined above:

An illustrative heterocyclic oxaadamantyl ligand is1,3,5,7-tetramethyl-6-phenyl-2,4,8-trioxa-6-phosphaadamantane (TMPTPA):

In some aspects, the conditions sufficient to yield a catalyst precursorsolution include a temperature within a range of from 0 degreescentigrade (° C.) to 100° C., preferably from 5° C. to 60° C.

In some aspects, the number of equivalents of a phosphine is one or two.

In some aspects, the solvent blend has a 1-methoxy-2,7-octadiene contentwithin a range of from 0.1 weight percent (wt %) to 50 wt %, based upontotal solvent blend weight. In related aspects, the solvent blend has a1-methoxy-2,7-octadiene content within a range of from 10 wt % to 25 wt%, based upon total solvent blend weight.

In some aspects, the catalyst precursor solution has a palladiumconcentration that ranges from 0.02 wt % to 2 wt %, preferably from 0.02wt % to 1.5 wt % more preferably from 0.1 wt % to 1 wt % and still morepreferably from 0.25 wt % to 0.6 wt %, as palladium metal, based ontotal catalyst precursor solution weight.

In some aspects, the conditions sufficient to yield the above-notedprecursor include concentrations of MOD-1 from 1 equivalent perpalladium to 500 equivalents per palladium, temperatures that range from0° C. to 100° C., and reaction times that range from 1 hour to 1000hours. As a general rule, with an increase in either or both oftemperature and MOD-1 concentration, precursor formation becomes morerapid. One may adjust either or both to provide a convenient time forthe conversion. In general for commercial operation, it is convenientthat the precursor be formed in 2-100 hours, although this is notabsolutely necessary. Reaction times of 100 hours or less can beachieved at temperatures from 30° C. to 60° C., with concentrations ofMOD-1 from 10-50 wt % (about 75-400 molar equivalents based on palladiumat 0.1 weight percent). The processes of various aspects of thisinvention have utility in that they yield a catalyst precursor thatrequires little, preferably no, induction time before it enters into thetelomerization reaction.

Ligands suitable for use in the process and in making the catalystprecursor include tertiary arylphosphines, formulaically represented asAr_(n)PR_((3−n)), where n=1-3, and Ar is independently selected from agroup consisting of substituted or unsubstituted aromatic groups.Illustrative substituents for substituted aromatic groups include alkyl,aryl, alkaryl, aralkyl, alkoxy, halo, silyl, and amino groups. Thetertiary arylphosphines may be fused with other substituted orsubstituted carbocyclic or heterocyclic aromatic or aliphatic rings. Ris selected from the group of substituted or unsubstituted alkyl, andmay contain additional heteroatoms, such as oxygen, nitrogen, silicon,and sulfur. In the case where n=1, R groups may be connected to formcarbo- or hetero-cyclic rings or polycarbo- or polyhetero-cyclic rings.Furthermore, R and Ar groups may be connected to form rings.

Other suitable ligands include tertiary phosphines representedformulaically as R¹PR² wherein R¹ is an aryl moiety or a substitutedaryl moiety or an alkyl moiety or a heteroatom-containing alkyl moietyand R² is independently a heterocyclic oxaadamantyl group. Illustrativesubstituents for substituted aromatic groups include alkyl, aryl,alkaryl, aralkyl, alkoxy, halo, silyl, and amino groups. When R¹ is analkyl group, suitable groups include primary, secondary or tertiaryC₁-C₁₂ (one to twelve carbon atom(s)) groups, each of which may containa heteroatom such as oxygen, nitrogen, silicon, and sulfur. In preparingcatalyst precursor solutions, such other suitable ligands benefit fromusing a solvent blend that contains MOD-1, but some of them react fastenough without MOD-1 that their performance is acceptable.

Prepare a catalyst precursor solution by bringing together, at aminimum, a source of Pd, preferably palladium acetyl acetonate, one ormore equivalents of a tertiary phosphine ligand, an alkanols, preferablymethanol, and methoxyoctadiene, preferably 1-methoxy-2,7-octadiene,under conditions sufficient to make an amount of a catalyst precursorthat contains or comprises palladium, tertiary arylphosphine ligand, anda ligand derived from the methoxyoctadiene and may be representedformulaically by [(Ar_(n)PR_((3−n)))_(x)PdY]^(0 or +), where n=1-3, andx=1 or 2, and Y is a ligand derived from methoxyoctadiene. In someaspects of this invention, the ligand Y may be octadienyl. Theconditions include those noted hereinabove.

In making the catalyst precursor solution, suitable amounts ofmethoxyoctadiene range from about 0.1 wt % (about 1 molar equivalent at0.1 weight % palladium) to 50 wt %, (about 400 molar equivalents at 0.1weight percent palladium) in each case the weight percent is based ontotal catalyst precursor solution weight. The solvent blend has a1-methoxy-2,7-octadiene content that is preferably within a range offrom 10 weight percent to 50 weight percent, based upon total solventblend weight. At a minimum, the amount is sufficient to convert at leastsome of the above minimum components used in forming the catalystprecursor solution to the catalyst precursor, with an amount sufficientto convert all of such components to the catalyst precursor beingpreferred. In the latter instance, use an amount of the methoxyoctadienethat is at least an equivalent molar stoichiometric amount to the amountof palladium. For example, if Pd constitutes 0.1 wt % of the catalystsolution, then methoxyoctadiene should be present in an amount of atleast 0.1 wt %, each wt % being based on total catalyst solution weight.Larger amounts of methoxyoctadiene relative to the amount of Pd can be,and frequently are, used to, among other things, lead to MOD-1 modifiedcatalyst precursor formation at a faster rate than one can attain withequivalent molar stoichiometric amounts.

GENERAL EXPERIMENTAL PROCEDURE

In a general procedure for conducting the telomerization reaction, placedi-n-butyl ether (GC internal standard)(Bu₂O), methanol,methylcyclohexane (MeCy) solvent, a precatalyst stock solution preparedas detailed below (1 milliliter (mL)) and 0.5 mL of a 0.01932 molarsolution of sodium methoxide (sometimes referred to as sodium methylate)(NaOMe) in methanol in a Fischer-Porter bottle. Unless otherwisespecified, effect reactions with MeOH present at a 14 molar level,adjusting other components (also known as “reagents”) in the bottle toaccount for changes in reaction chemistry. Seal the bottle with a valveequipped with a septum port. Outside a glove box, distill approximately5 mL of butadiene into a gas-tight syringe, determining the actualamount of butadiene in the syringe by weighing the syringe before andafter injecting the butadiene into the bottle through the septum withthe syringe needle placed below the surface of bottle contents. Placethe butadiene-containing bottle in a preheated oil bath (40° C., 60° C.or 70° C. as shown below) equipped with a magnetic stirrer bar and allowthe contents of the bottle to react for a select period of time (e.g. 4hours). Sample bottle contents at 30 minutes, 1 hour, 2 hours and 4hours after initiating reaction to develop a conversion versus timeprofile to determine whether there is an induction period or not. Use a24 inch (61 cm) needle equipped with a gas-tight valve to draw thesamples from the bottle for use in gas chromatography analysis.

Example (Ex) 1: Preparation of TCMPP Pre-Catalyst Stock Solution

Using a glove box, dissolve 0.0147 gram (g) (0.0000483 mole) ofpalladium acetyl acetonate [(Pd(acac)₂], 0.0440 g (0.0000966 mole) ofligand, 0.134 g (0.00096 mole) of MOD-1, and 0.25 mL of a stock solutionof acetic acid (AcOH) in methanol (0.1932 M) in approximately 24.75 mLmethanol to a total volume of 25 mL and allow the resulting precatalyststock solution to stir at ambient temperature (nominally 25° C.) for atleast three days before use. Represent the ligand schematically as:

Comparative Example (CEx) A

Make a pre-catalyst stock solution as in Ex 1, but omit the MOD-1. Ex 2:

Conduct a telomerization reaction at 40° C. using the pre-catalyst stocksolution prepared in Ex 1. Show analytical results in Table 1 below.

TABLE 1 Butadiene MOD-1 MOD-1 Time Conversion (%) Selectivity (%) Yield(%) 30 min 43.2/44.1 97.3/97.2 42.0/42.9 1 hour 47.8/49  97.3/97.246.5/47.7 2 hours 53.2/54.5 97.3/97.5 51.7/53.1 4 hours 61.4/69.397.2/97.3 59.7/67.4

CEx B

Replicate Ex 2 but with an aliquot of the pre-catalyst stock solutionprepared in CEx A. Show analytical results in Table 2 below.

TABLE 2 Butadiene MOD-1 MOD-1 Time Conversion (%) Selectivity (%) Yield(%) 30 min   17.2 96.6 16.6 1 hour  22.9 97.0 22.2 2 hours 20.2 96.719.5 4 hours 26.9 96.8 26.0

CEx C

Replicate Ex 1, but change the amount of MOD-1 from 10 equivalents toabout 1200 equivalents per palladium and use one molar equivalent ofTCMPP per molar equivalent of Pd(acac)2.

CEx D: Replicate Ex 3, but omit the MOD-1. 1CEx E

Conduct a telomerization reaction at 70° C. with an aliquot of thepre-catalyst solution prepared in CEx C. Show analytical results inTable 3 below.

TABLE 3 Butadiene MOD-1 MOD-1 Time Conversion (%) Selectivity (%) Yield(%) 30 min   30.9 92.1 28.4 1 hour  48.9 96.6 47.2 2 hours 68.8 96.666.5 4 hours 69.8 96.5 67.4

CEx F

Conduct a telomerization reaction at 70° C. with an aliquot of thepre-catalyst solution prepared in CEx D. Show analytical results inTable 4 below.

TABLE 4 Butadiene MOD-1 MOD-1 Time Conversion (%) Selectivity (%) Yield(%) 30 min   60.5/44.8  96.5/96.1 58.3/43.1 1 hour  65.9/44.6 96.3/9663.4/42.8 2 hours 72.3/45.5 96.2/96 70.0/43.7 4 hours 77.5/44.9 96.2/9674.6/43.1

These comparative examples are included to demonstrate the conditionsfor which the MOD-1 modification of the precatalyst is ineffective. Inthese examples, the MOD-1-modified pre-catalyst is less efficient andconverts less butadiene than the unmodified counter example. It islikely that there is a significant inhibition of MOD-1 within thisregime of 1000+ equivalents of MOD-1 to palladium.

Ex 3

Replicate Ex 1, but use the ligand1,3,5,7-tetramethyl-6-phenyl-2,4,8-trioxa-6-phosphaadamantane (TMPTPA)represented schematically below instead of TCMPP.

Prepare two pre-catalyst stock solutions from this solution:

Ex 3.1

For the first pre-catalyst stock solution, take 5 mL of the 25 mLsolution and add (0.0170 g, 0.000122 moles) of MOD-1 to provide apre-catalyst stock solution.

Ex 3.2

For the second pre-catalyst stock solution, use aliquots of the stocksolution of Ex 3 as prepared.

Ex 4

Conduct a telomerization reaction at 40° C. using an aliquot of thepre-catalyst stock solution prepared in Ex 5.1. Show analytical resultsin Table 5 below.

TABLE 5 Butadiene MOD-1 MOD-1 Time Conversion (%) Selectivity (%) Yield(%) 30 min   13.4 93.6 12.5 1 hour  33.1 95.5 31.6 2 hours 45.1 95.342.9 4 hours 56.9 95.1 54.1

CEx G

Replicate Ex 4, but use an aliquot of the pre-catalyst stock solution ofEx 3.2. Show analytical results in Table 6 below.

TABLE 6 Butadiene MOD-1 MOD-1 Time Conversion (%) Selectivity (%) Yield(%) 30 min   1.9 61.6 1.2 1 hour  2.0 65.8 1.3 2 hours 4.8 84.1 4.0 4hours 44.0 95.2 41.9

Ex 5

Use the pre-catalyst stock solution from Ex 3.1 but change the generalprocedure to include 1.0 mL of the sodium methoxide stock solution and12 mL of methanol. Run the telomerization reaction at 40° C. Showanalytical results in Table 7 below.

TABLE 7 Butadiene MOD-1 MOD-1 Time Conversion (%) Selectivity (%) Yield(%) 30 min   41.1 96.0 39.5 1 hour  51.5 95.7 49.2 2 hours 65.1 95.362.0 4 hours 76.7 95.1 72.9

CEx H

Replicate Ex 5 but use the pre-catalyst stock solution from Ex 3.2. Showanalytical results in Table 8 below.

TABLE 8 Butadiene MOD-1 MOD-1 Time Conversion (%) Selectivity (%) Yield(%) 30 min   3.1 76.3 2.4 1 hour  7.3 88.2 6.4 2 hours 9.6 90.3 8.7 4hours 65.3 95.1 62.1

Ex 6

Replicate Ex 1, but use the ligand TMPTPA at half the molarconcentration of ligand.

CEx I

Replicate Ex 6 but without the addition of MOD-1.

Ex 7

Conduct a telomerization reaction at 40° C. using an aliquot from thepre-catalyst stock solution from Ex 6. Show analytical results in Table9 below.

TABLE 9 Butadiene MOD-1 MOD-1 Time Conversion (%) Selectivity (%) Yield(%) 30 min   64.1 94.7 60.7 1 hour  77.9 95.2 74.9 2 hours 84.1 95.180.0 4 hours 90.0 95.0 85.5

CEx J

Conduct a telomerization reaction at 40° C. with an aliquot of thepre-catalyst solution from CEx I. Show analytical results in Table 10below.

TABLE 10 Butadiene MOD-1 MOD-1 Time Conversion (%) Selectivity (%)Yield(%) 30 min   33.6 92.9 31.2 1 hour  54.3 94.6 51.4 2 hours 71.095.0 67.4 4 hours 81.3 94.7 77.0

Ex 8

Replicate Ex 1, but change the ligand to1,3,5,7-tetramethyl-6-(2-methoxyphenyl)-2,4,8-trioxa-6-phosphaadamantane(TMPTPA-OMe), represented schematically below, change the amount ofequivalents of MOD-1 to 10, and reduce the molar equivalents ofTMPTPA-OMe to half (one equivalent per Pd).:

CEx K

Replicate Ex 8, but omit the MOD-1.

Ex 9

Conduct at telomerization reaction at 40° C. with an aliquot of thepre-catalyst solution prepared in Ex 8. Show analytical results in Table11 below.

TABLE 11 Butadiene MOD-1 MOD-1 Time Conversion (%) Selectivity (%)Yield(%) 30 min   15.2 95.1 14.5 1 hour  36.3 96.4 35.0 2 hours 63.696.7 61.5 4 hours 81.2 96.7 78.5

CEx L

Conduct a telomerization reaction at 40° C. with an aliquot of thepre-catalyst solution prepared in CEx K. Show analytical results inTable 12 below.

TABLE 12 Butadiene MOD-1 MOD-1 Time Conversion (%) Selectivity (%)Yield(%) 30 min   1.5 74.0 1.1 1 hour  4.6 89.9 4.1 2 hours 18.2 95.417.4 4 hours 50.7 96.5 48.9

Ex 10

Conduct at telomerization reaction at 70° C. with an aliquot of thepre-catalyst solution prepared in Ex 8. Show analytical results in Table13 below.

TABLE 13 Butadiene MOD-1 MOD-1 Time Conversion (%) Selectivity (%)Yield(%) 30 min   70.9 94.9 67.3 1 hour  83.4 95.0 79.2 2 hours 90.294.9 85.6 4 hours 93.0 94.9 88.3

CEx M

Conduct a telomerization reaction at 70° C. with an aliquot of thepre-catalyst solution prepared in CEx K. Show analytical results inTable 14 below.

TABLE 14 Butadiene MOD-1 MOD-1 Time Conversion (%) Selectivity (%)Yield(%) 30 min   55.5 94.5 52.4 1 hour  73.6 94.5 69.6 2 hours 89.094.5 84.1 4 hours 95.3 94.5 90.1

Several points of note emerge from a review of the above examples andcomparative examples. First, addition of MOD-1 to methanol to create asolvent blend results in at least a substantial decrease in duration andin some cases elimination of an induction period before the catalystprecursor is ready to take an active part in telomerization. Second, useof a solvent blend (methanol and MOD-1) in preparation of telomerizationcatalyst precursor results in an increase in overall conversion ofbutadiene at a reaction temperature below 70° C. relative to conversionobtained with a telomerization catalyst precursor prepared in theabsence of MOD-1 (methanol only) of at least 10%. Third, thetelomerization catalyst precursor is stable in that it does not formsolids that precipitate out of solution under the conditions stated inthe examples (Ex 1-12) whereas under the same conditions save for use ofmethanol rather than a blend of methanol and MOD-1, a visuallydiscernible amount of telomerization catalyst precursor effectivelyprecipitates out of solution. The enhanced stability of the inventivetelomerization catalyst precursor has an economic benefit in that onemay decrease the amount of ligand used in its preparation.

Ex 11: Preparation of MOD-1 Modified Catalysts

Use a 1 gallon laboratory reactor to prepare the pre-catalyst solution.Operate the reactor with a reactor jacket set point temperature of 35°C., and a methanol condenser set point temperature of 5° C. Load thereactor with 53.9 g TCMPP and 17.9 g Pd(acac)₂, and then purge thereactor with N₂ at 0.5 scfh (14.2 liters/hour). Load the solventreservoir with 1480.5 g methanol and sparge the reservoir with N₂.Transfer 419 g methanol to the reactor at 18 mL/min over 30 min. Startagitation of reactor contents at 580 rpm. Transfer an additional 838 gof methanol to the reactor at 152 mL/min over 7 min. Add aqueous aceticacid solution (3.71 g acetic acid+1.59 g water) to the reactor withcontinued agitation. Add remaining methanol (223.5 g) to the reactor at151 mL/min over 6 min, followed by 493.5 g of MOD-1. Reduce the reactorN2 purge rate to 0.15-0.25 scfh (4.3-7.1 liters/hour). The overallpre-catalyst composition is designated as: Pd/TCMPP/acetic acid molarratio of 1.00/2.01/1.04 and palladium concentration of 0.31 wt %. Allowthe pre-catalyst solution to stir at 35° C. over 22 days at 580 rpm,sampling the pre-catalyst solution on days 1, 8, 15 and 22 fortelomerization activity evaluation. Visual observation shows no evidenceof solids precipitation over a period of 578 hours.

Take samples of the reactor contents on Day 1 using Pressure-lok™gas-tight syringes, and transfer the samples to a glove box maintainedat less than 1 ppm oxygen. Periodically determine composition of suchsamples by P³¹ NMR spectroscopy (400 megahertz (MHz) at −40° C. over anacquisition time of two to four hours, adding approximately 10% ofD₄-methanol as a lock solvent). Control reactor content temperatureeither by a heated solvent bath, or by the glove box air-conditioner.Periodically take temperature measurements over the timescale of thereactions to confirm that temperature is controlled to ±1° C. In somecases, add an internal standard, triphenylphosphine oxide, so thatabsolute concentrations can be determined. See Table 15 below for P³¹NMR composition data.

TABLE 15 Mole fraction of phosphorus by species* Initial MOD-1 OtherTime TCMPP Pre- Modified Uniden- (hrs) TCMPP Oxide Phosphonium catalystCatalyst tified 0 0.02 0.04 0.00 0.91 0.00 0.03 16 0.01 0.04 0.02 0.770.15 0.01 23 0.02 0.03 0.05 0.66 0.24 0.00 49 0.00 0.06 0.13 0.12 0.680.00 64 0.00 0.03 0.16 0.00 0.82 0.00 333 0.00 0.07 0.13 0.00 0.77 0.03*TCMPP if free ligand, TCMPP Oxide is the phosphine oxide, Phosphoniumis [(2-OMe, 5-Cl—C₆H₃)₃P(CH₂CH═CHCH₂CH₂CH₂CH═CH₂)]⁺, Initial precatalystis {(2-OMe, 5-Cl—C₆H₃)₃P}₂Pd(acetyl acetoante)]⁺, MOD-1 modifiedcatalyst is [(Ar_(n)PR_((3−n)))_(x)PdY],

This Ex 11 (with MOD-1 addition) shows that the initial pre-catalyst isconverted to a MOD-1 modified catalyst over about 70 hours, after whichno further significant changes occur. There is no discernible evidenceshowing formation of [Pd(TCMPP)₂(CH₂═C{(C═O)Me}₂].

Table 16 below shows the catalyst activity and selectivity of the MOD-1modified catalyst compared with the performance of the control catalystthat was not treated with MOD-1.

TABLE 16 Butadiene Conversion (%) Control: No MOD-1 Butadiene Conversion(%) after Catalyst Pre-treatment Aging with MOD-1 for Reaction Time onDay 1 1 Day 8 Days 15 Days 22 Days  12-15 min 3.3 20.1 58.2 65.5 66.3    45 min 24.5 52.0 67.0 74.5 72.7  80-90 min 50.8 67.7 73.7 77.2 80.2130-150 min 67.9 79.9 81.6 83.4 82.0 220-240 min 76.9 84.3 85.6 86.784.8 Final MOD-1 96.4 95.8 93.3 96.6 96.3 Selectivity (%)

This data shows that the pre-catalyst is converted to a new, stablecomplex, [(Ar_(n)PR_((3−n)))_(x)PdY], which exhibits improved activityat 60° C. in telomerization, with a decrease in an induction period.

CEx K-O: Solids Precipitation from Unmodified Pre-Catalyst Solutions

Replicate Ex 11 with changes in palladium complex as shown in Table 17below and elimination of MOD-1. A visual examination of catalystsolutions shows that solids ([Pd(TCMPP)₂(CH₂═C{(C═O)Me}₂) begin toprecipitate out of solution at 338 hours in the 1 gallon reactor at 20°C. with an initial palladium concentration of approximately 0.31 weightpercent. At a smaller scale in the glove box under otherwise similarconditions, precipitation out of solution begins at approximately 310hours (CEx L). Table 17 below shows precipitation times of catalyst thathave not been modified by MOD-1 addition.

TABLE 17 Initial Palladium Time of first Concentration evidence ofConcentration of Temperature (Weight % as precipitation[Pd(TCMPP)₂(CH₂═C{(C═O)Me}₂] Experiment (° C.) Pd) (hrs) at time ofprecipitation(Weight %) CEx K 31 0.305 76 0.79 CEx L 30 0.305 115 0.57CEx M 20 0.305 310 0.68 CEx N 31 0.153 82 0.70 CEx O 31 0.102 120 0.64

CEx K-O show that, absent modification with MOD-1, solids precipitationoccurs, such that the initially formed pre-catalyst is converted to anew, largely insoluble species, [Pd(TCMPP)₂(CH₂═C{(C═O)Me}₂] Theinsoluble species can, in turn, foul process equipment.

CEx P

Add 2 wt % of isolated, solid [Pd(TCMPP)₂(CH₂═C{(C═O)Me}₂] to a freshlyprepared pre-catalyst solution and stir for half an hour in a glove boxto allow dissolution of the solid and to achieve solid-liquidequilibrium. Immediate P³¹ NMR analysis shows a palladium (0) complexconcentration in solution at room temperature (nominally 20° C.) of 0.08wt %.

Ex 12

In a glovebox, dissolve degassed glacial acetic acid (AcOH) (55.3 μL) indegassed MeOH to a volume of 5 mL (0.1932 M AcOH in MeOH) to form AcOHsolution. Dissolve palladium(II) acetylacetonate (Pd(acac)₂) (0.0110 g,0.0000362 moles), 2,3-(dihydrobenzofuran-7-yl)diphenylphosphine (DHBDPP,illustrated below) (0.0220 g, 0.0000724 moles) and 0.1875 mL of the AcOHsolution in 15.0 mL MeOH and 3.6 mL MOD-1 to form a precatalyst stocksolution. Allow the precatalyst solution to stir for 6 days at 25° C.before use.

Add dibutyl ether (Bu₂O, 5 mL), 12.8 M MeOH (10.96 mL), anhydrousdegassed methylcyclohexane (MeCy, 1.6 mL), the precatalyst stocksolution (1 mL), and a portion of a solution of sodium methoxide (NaOMe)(1.0 mL) in MeOH (0.01932 M) to a Fisher-Porter bottle. Seal theFisher-Porter bottle with a valve equipped with a septum port.

Use the above-noted General Experimental Procedure, a temperature of 40°C., a reaction time of 4 hours and sampling at 30 minutes, 60 minutes,120 minutes and 240 minutes followed by GC analysis to evaluateperformance of the MOD-1 modified pre-catalyst. See Table 18 below for asummary of such performance.

CEx Q

Replicate Ex 12, but eliminate the MOD-1 addition, and change theamounts of palladium(II) acetylacetonate (Pd(acac)₂) to 0.0980 g(0.00003217 mole), DHBDPP to 0.0196 g(0.00006441 mole) and AcOH solutionto 0.167 mL AcOH in 16.5 mL MeOH.

Ex 13

Replicate Ex12, but change the oil bath temperature to 60° C.

CEx R

Replicate CEx Q, but change the oil bath temperature to 60° C.

Ex 14

Replicate Ex 12, but with the following changes: in making theprecatalyst solution, use the following amounts: 0.0147 g (0.0000483mole) of Pd(acac)₂, 0.250 mL of AcOH stock solution, 20 mL MeOH and 4.75mL MOD-1; substitute triphenylphosphine (TPP, shown schematically below)(0.0253 g, 0.0000965 moles) for DHBDPP; allow the precatalyst to age for7 days before use; and, in loading the Fisher-Porter bottle, use 0.5 mLof a solution of sodium methoxide in MeOH (0.01932 M) and 11.46 mL MeOH.

CEx S

Replicate Ex 1, but with the following changes: in making of theprecatalyst solution, use the following amounts: 0.0147 g (0.0000483miles) of Pd(acac)₂, 0.250 mL of AcOH stock solution and 24.75 mL MeOH.Substitute TPP (0.0253 g, 0.0000965 moles) for DHBDPP. In loading theFisher-Porter bottle, use 0.5 mL of a solution of sodium methoxide inMeOH (0.01932 M) and 11.46 mL MeOH.

Ex 15

Replicate Ex 14, but heat the oil bath 60° C.

CEx T

Replicate CEx S, but heat the oil bath 60° C.

TABLE 18 Final MOD-1 Butadiene Conversion (%) Selectivity Ex LigandMOD-1 [MeOH] NaOMe:Pd L:Pd 30 min 1 hr 2 hr 4 hr (%) Ex 12 DHDDPP Yes12.7 10:1 2:1 17.1 30.0 45.4 62.0 96.6 C Ex Q DHDDPP N 12.7 10:1 2:1 7.119.0 37.7 60.4 96.6 Ex 13 DHDDPP Yes 12.7 10:1 2:1 38.4 55.4 74.3 83.895.0 C Ex R DHDDPP N 12.7 10:1 2:1 17.4 36.7 65.3 83.4 95.2 Ex 14 TPPYes 12.7  5:1 2:1 7.0 13.4 24.7 43.2 95.6 C Ex S TPP N 12.7  5:1 2:1 2.76.8 18.2 38.6 95.0 Ex 15 TPP Y 12.7  5:1 2:1 25.2 40.6 62.5 80.7 93.2 CEx T TPP N 12.7  5:1 2:1 8.0 31.2 62.0 80.5 92.8

The data in Table 18 illustrate several points. First, the addition ofMOD-1 to pre-catalyst solutions of DHDDPP and TPP generatescatalytically competent complexes that result in a much faster initialrate of butadiene conversion than the pre-catalyst solutions that do notcontain MOD-1 (compare the 30 min time points for all examples in Table18). Second, the addition of MOD-1 to the pre-catalyst solutions ofDHDDPP and TPP results in a higher overall conversion to products afterthe 4 hour reaction time. Third, the MOD-1 modification of thepre-catalyst does not affect the selectivity of the process. Thus, themodification of pre-catalyst solutions of DHDDPP and TPP with MOD-1ultimately results in a higher yield of the desired product for all thedemonstrated cases.

What is claimed is:
 1. A process for preparing a telomerization catalystprecursor used in telomerization of butadiene that comprises dissolvingone equivalent of palladium acetyl acetonate and from one to threeequivalents of a tertiary phosphine ligand in a solvent that comprisesmethanol and, optionally, 1-methoxy-2,7-octadiene under conditionssufficient to yield a catalyst precursor solution wherein the tertiaryphosphine ligand is represented formulaically as R¹PR² and where R¹ isan aryl moiety or a substituted aryl moiety or an alkyl moiety orheteroatom-containing alkyl moiety with 1 to 12 carbon atoms, and R² isindependently a heterocyclic oxaadamantyl group.
 2. The process of claim1 wherein the phosphine-containing heterocyclic oxaadamantyl groups isrepresented schematically as shown below:


3. The process of claim 2 wherein the heterocyclic oxaadamantyl ligandis 1,3,5,7-tetramethyl-6-phenyl-2,4,8-trioxa-6-phosphaadamantane(TMPTPA) or1,3,5,7-tetramethyl-6-(2-methoxyphenyl)-2,4,8-trioxa-6-phosphaadamantane(TMPTPA-OMe).
 4. The process of claim 1, wherein the conditions includea temperature within a range of from 0 degrees centigrade to 100 degreescentigrade.
 5. The process of claim 1, wherein the conditions include atemperature within a range of from 5 degrees centigrade to 60 degreescentigrade.
 6. The process of claim 1, wherein the number of equivalentsof a tertiary phosphine ligand is one or two.
 7. The process of claim 1,wherein the solvent comprises 1-methoxy-2,7-octadiene.
 8. The process ofclaim 7, wherein the solvent blend has a 1-methoxy-2,7-octadiene contentwithin a range of from 0.1 weight percent to 50 weight percent, basedupon total solvent blend weight.
 9. The process of claim 7, wherein thesolvent blend has a 1-methoxy-2,7-octadiene content within a range offrom 10 weight percent to 25 weight percent, based upon total solventblend weight.
 10. The process of claim 1, wherein the catalyst precursorsolution has a palladium concentration that ranges from 0.02 weightpercent to 2 weight percent, as palladium metal, based on total catalystprecursor solution weight.
 11. The process of claim 1, wherein thecatalyst precursor solution has a palladium concentration that rangesfrom 0.1 weight percent to 1 weight percent, as palladium metal, basedon total catalyst precursor solution weight.
 12. The process of claim 1,wherein the telomerization catalyst precursor remains in solution for aperiod of at least 360 hours at a temperature within a range of from 5°C. to 60° C. and a palladium concentration exceeding 0.1 weight percent.